>> we will once again be an industry leader, worthy of the name american airlines. america's flag carrier. >> reporter: if approved, the deal would make american the world's largest airline. but after so many mergers in recent years, only four airlines, american, delta, united and southwest, would be left with 70% of the u.s. market. while airfares haven't risen much in recent years, experts warn, less competition could ultimately drive up prices. >> if you're looking out over the next three or four years of your vacation plans you'll average between 5 and 10% airfare increases year over year once you hit 2014. >> concerned about the overall number of flights available, the cost of those flights. >> more and more mergers, prices are worse, choices are less. doesn't add up. >> reporter: for now, both usairways and american will continue to fly independently. passengers will fly the airline on which they're booked.